The present invention generally pertains to radar systems and is particularly directed to an improvement in a coherent pulse radar system. Referring to FIG. 1, a typical coherent pulse radar system includes an antenna 10 for transmitting and receiving radar signals; a reference frequency source oscillator 11 for providing a signal having a given reference frequency; a transmitter amplifier 12 for amplifying the reference frequency signal to provide a transmission signal to the antenna 10 via a duplexer 13 for transmission during a transmitting interval; a local oscillator circuit 14 for responding to the reference frequency signal to provide an offset frequency signal that has a frequency that is offset from the given reference frequency; and a mixer circuit 15 for mixing the received radar signal with the offset frequency signal to provide an intermediate frequency signal on line 16 during a receiving interval.
In a coherent pulse radar system, the transmission signal and offset frequency signal track one another in frequency with a relatively low frequency difference as determined by the offset of the offset frequency signal from the reference frequency signal. This difference in frequency is obtained by generating a sideband frequency in the local oscillator 14 that is offset in frequency from the given frequency of the reference frequency signal.
The power of the reference source oscillator 11 is shared by the transmitter amplifier 12 and the local oscillator 14. Typically, a power divider 17 is employed to divide the limited available power so that 50% of the available power is provided to the transmitter amplifier and 50% is provided to local oscillator. In solid state microwave/millimeter wave coherent pulse radar systems, such power division results in diminished system performance; or it may necessitate additional amplifier stages in the transmitter amplifier 12.